Procetss for manufacture of chloride of potassium



March 22, 1932.

Original Filed June 6, 1928 Sheets-Sheet l STEAM RETURN CIRCULATION I OF PORTION OF MOTHER LIQUOR 15 15 a I l4 'O' MOTHER LIQUOR WA SH WA 'T'ER CONDENSEK WASH E 'i m g m z 2: Q

GROUND WYOMING/TE v a V ENTOR.

STEAM R. D. PIKE ET AL PROCESS FOR MANUFACTURE OF CHLORIDE OF POTAS SIUM AND CARBONATES OF SODIUM AND POTASSIUM March 22, 1932.

Re. 18,393 2 Sheets-Sheet -0rig inal Filed June 6, 1928 LISRSEQQR 3.22% Sh T ll wk Ggtoxi 9536 1 29x53 turn:

Reisauied' Mar. 22, 1932 UNITED STATES PATENT OFFICE .ROBERT D. PIKE, OF DIABLO, ROSS CUMMINGS, 0F BERKELEY, AND LEO V. STECK, OF

OAKLAND, CALIFORNIA; SAID CUMMINGS AND SAID STECK ASSIGNORS TO SAID PIKE PROCESS FOB MANUFACTURE OF CHLORIDE OF POTASSIUM AND CARBONATES OF SODIUM AND POTASSIUM Original No. 1,770,995, dated July 22, 1930, Serial No. 283,405, filed June 6, 1928. Application for reissue filed January 11, 1932. Serial No. 585,980.

Our present invention relates to aprocess for the manufacture of carbonates of sodium and potassium and chloride of potassium, and more particularly to a process for the manufacture of the above from the natural resources located in and near Green River, VVyoming. I

This application is a continuation in part of a former application filed by us on March 6, 1928, and designated as Serial Number 259,422.

Near Green River, Wyoming, there is a large deposit of potassium-silicate rock known as wyomingite, of which leucite is the puncipal potash bearing constituent and at Green River there is available by pumping from shallow wells, a brine composed principally of sodium carbonate with a lesser content of sodium chloride.

It is an object of our present invention to manufacture from these two important raw materials, or from like or analogous materials occurring elsewhere, commercially pure chloride of potassium, commercially pure sodium carbonate, and a brine carrying principally potassium carbonate in solution.

A method for carrying out our invention, in which the sodium carbonate is not pro- 'duced as such but is circulated in the process,

is illustrated in Figure 1 of the accompanying flow sheets, in which 10 designates an autoclave or other suitable type of pressure yessel illustrated as a tumbling autoclave adapted to treat ground wyomingite under agitation and at substantially 200 pounds steam pressure with a mixed solution of sodium carbonate and Green River soda brine which is prepared in a dissolving tank 11, as will hereinafter appear. After treatment in this autoclave for a suitable length oftime to ex tract from the wyomingite substantially all of the potassium which is subject to base exchange with sodiuin under the conditions obtaining, the pulp is removed to a storage tank 12 and is thence pumped to a continuous filter 13 where the potash bearing solution is removed from the solids and the latter washer. The washed solids are the tails and are rejected. The solution and wash water pass to 16 of any suitable type and passes to a thickener 17 and thence to a suitable filter 18. The clear liquor from the filter 18 and the thickener 17 join and pass to the evaporator supply tank 14. The dewatered sodium carbonate mono hydrate is transported to-the dissolving tank 11, previously referred to, where it is dissolved in the Green River soda brine. The solution thus formed, together with the ground wyomingite forms the feed to the. autoclave 10. The strong solution from the last or high pressure effect of the evaporators 15 goes to the crystallizer 20, where it is cooled to 25 to30 C. This cooling causes pure KCl to crystallize, the chlorine associated therewith corresponding to the major part of the chlorine which is introduced into the system as sodium chloride in the Green River. soda brine.

The pulp from the crystallizer 20 then goes to a centrifugal separator 21, where KCl crystals are separated out and Washed. The Wash water goes to a tank 22 whence it is pumped back to the evaporator supply tank 14. The mother liquor from the centrifuge 21 next goes to the tank 23. It is desirable to have the chloride content of this mother liquor as low as possible, and to have the ratio K O/Na O as high as possible.

In the. two quantitative examples of the carrying out of the method given below, it is shown, as we have discovered, that this end is served by returning in circulation to the evaporator supply tank 14 a portion, preferably one-half, of the solution from tank 23.

The not advance of solution passing forward from the tank 23 contains all of the potash which was removed from the wyomingite in the autoclave 10, except that removed as chloride of potassium (KGl) in 21, almost entirely in the form of otassium carbonate. This finished potash rine can be employed for the manufacture of commercially pure potassium carbonate as disclosed in our cope-riding application filed March 6, 1928, Serial No. 259,423, or for the manufacture of crude monopotassium phos Green River soda brine S Per cent c. gr; 1.100 30-- Na o 6.74 NaOl 2.32 M200 8.30 NaHCO 0.71 Na s- 0.18 vN'a SO .04 Total solids 11.05

. Wymningz'te K 0 11.48 'Na,0 1.32 SiO 51.70 A1203 Fe O= 4.20 FeO 1.28 CaO 6.80

M O 7.60 P 6, 2.75

The wyomingite is ground dry to have the following screen analysis:

7 Per cent Example N o. 1 One quarter of solution from tank 23'is returned in circulation to tank 4. The feed to the autoclave 10 is in batches which per 100 pounds wyomingite follow: I

. .Pounds Wyomingite 100 Return sodium carbonate mono hydrate 21.8 Green River soda brine 100.8

After the treatment in the autoclave 10, the removal and washing of the tails and the addition of the return solution from tank 23 and the washwaters, the composition of the evaporator feed per ton (2000 pounds) of vAm. -Chem. Soc.

K50, produced as KOl crystals and as K 00,

in the finished brine, is as follows:

Pounds KGl .777 K COQtL i; Naooa 5514 E 0 30500 A method for producing from such a solution pure crystals of KCl and Na CO H O on the one hand and a substantially pure brine of K GO on the other, has not hitherto been known and discovery of such a method constitutes one of the principal features of our invention. We have discoveredthat if this brine be evaporated preferably at, or nearly at, atmospheric boiling temperatures, until the liquor becomes saturated with reference to both KCl and Na CO there will crystallize out durin this process of concentration 5440 poun s of pure Na CO H O per ton of K 0 as above defined, and that the water evaporated will amount to 25,331 pounds. Furthermore no crystallization of the N3|2GO3H2O occurs until there have been evaporated 13,255 pounds of Water. In car- Pounds KCl-.. 777 K2003 Na co 875 H O 4379 120 C. We have discovered that if thissolution is cooled in mechanical crystallizers to 25 C. fairly'rapidly, pure KCl crystallizes, in spite of the fact that the stable solid phase, which should be in equilibrium with the resulting solution according to Blasdale, J our. 45, 2935 (19 23) is KNaCO 6H O. The mother liquor remains supersaturated with respect to this latter salt and pure KCl crystals are recovered by centrifuging.

The solution from the crystallizer 20 contains the following per ton of K 0 as above defined;

One-quarter of this solution is returned in circulation to the evaporator feed and the balance is the net brine produced by the process. v

Ewample No. 2

One-half of the solution from tank 23 is returned in circulation to tank 14.

The feed to the autoclave 10 per 100 pounds of wyomingite is as follows:

Pounds Green River soda brine After the treatment in the autoclave, the removal and washing of the tails and the addition of the return solution from tank 23 and the wash waters, the composition of the evapabove defined, the following:

orator feed per ton (2000 poundskof K produced as KCl crystalsand as the finished brine,.is as follows:

Pounds Ko1 77s K2CQ, 4538 200, 5840 H20 31400 After evaporating in thesame manner as described under Example 1, a strong solution is produced which contains per ton K 0, as

Pounds KCl K2603 Na cO 1090- H O .1. 5660 If this solution is cooled as above described to 25 C it remains supersaturated to the stable solid. phase, KNaCO 6H O, and pure KClis crystallized. After this is removed by centrifuging, there remains in the mother liquor per ton of K 0 as above defined, the following: I Y

Pounds One-half of this solution is returned in circulation to the evaporator feed and the bal ance is the net brine produced by the process. The effect of increasing the circulation of strong brine after crystallizing the KCl is illustrated in the following summary.

Return 01% Returnol' of strong of strong brine brine M01 ratio loo Nae 2. 72! 3. 260 M01 ratio Col/Cl: 36.04 51.6 p

Our process is applicable to leaching with brines containing lesser or greater amounts of NaCl and greater or lesser amounts of Na CO than the Green River soda water.

As the content of NaGl decreases, the amount of liquor which it is necessary to circulate from tank 23 to tank 14, so as to produce a potassium carbonate brine of desired purity decreases until in the limiting case when theleach liquor is all sodium carbonate with no sodium chloride it is unnecessary to employ circulation in order to produce a brine in which the mol ratio K o/Na O is greater than 3; and, in such limiting case, the crystallizer would be eliminated and the strong liquor from the evaporator would be the finished carbonate brine. On the other hand, as the sodium chloride content in the leaching brine increases, a point is speedily reached where the flow sheet of Figure 1 is no longer adequate to produce a potassium carbonate brine of the desired purity, but the latter will contain undesirably large amounts of both sodium carbonate and potassium chloride.

If the sodium carbonate mono hydrate, instead of being returned in circulation in the 8 process, is removed and washed free from mother liquor, it is a commercially pure salt which can be used as such, or easily converted to soda ash or caustic soda. To do this, therefore,'constitutes a valuable variation of our process; but in so doing, the leaching brine becomes the Green River soda brine in which no sodium carbonate has been dissolved. In effect, therefore, the leaching brine which goes to the autoclave contains much more sodium chloride in relation to sodium carbonate than is the case in Figure 1, and the solution of this case, using the Green River soda brine, is virtually also thesolut-ion of the case involving the use of the flow sheet of Figure 1 with a brine containing a much larger amount 'ofsodium chloride than the Green River brine.

Figure 2 shows a flow sheet for use of the Green River sodabrine for leaching Wyomingite in which all of the sodium carbonate mono hydrate is removed. In Figure 2, 25 is a storage tank for the Green River soda brine, from whence it is'fed through a preliminary evaporator 26, where of its water is evaporated amounting to about 34,800 pounds c osed in the Pike case, previously referred to. For each ton of potash produce there are required about 25,000 pounds of wyomingite and 30,650 pounds concentrated brine containing Pounds Na O as NaCl 804 Na O as Na CO 3608 ater 26238 Hereafter, all figures named will be per ton (2000 pounds) of total K 0 produced. The potash rich solution which goes to the primary evaporator storage 29 from the leaching plant contains Pounds KCl 1934 K CO 1141 Na;CO 5297 H2O after addition of wash 34400 From tank 29 the liquor passesthrough primary salt-ing out'evaporators 30. These I evaporators are operated on the counter current principle, and the sodium carbonate mono hydrate which is salted out is removed. The latter is treated by suitable standard apparatus, not illustrated, for separation from the mother liquor and drying. The primary evaporators produce about 4660 pounds Na CO H O and evaporate about 25,000 pounds of water. The strong liquor from the primary evaporator 30 goes to a primary crystallizer 31 where it is cooled to from 25 to 30 C. producing about 1140 pounds KCl. The

'' latter is removed and free from the mother liquor by suitable well known apparatus not illustrated and the mother liquor goes to a secondary evaporator storage 32.

From the secondary evaporator storage tank 32 the liquor goes to secondary evaporators 33 where about 1225 pounds of Na CO H O is salted out and about 5000 pounds of water is evaporated. These secondary evaporators also work on the counter current principle. The strong liquor then goes to a secondary crystillizer 34 where it is cooled to a temperature of 25 to 30 C. and about 765 pounds of KCl is salted out. The

latter is removed from the primary crystal- 'lizer and of the clear liquor 80% is returned in circulation to the storage tank 32, the remaining 20% constituting the net yield of potassium carbonate. By the above procedure we have found that the final carbonate brine is made tocontain only a trace of KCl and to have a mol ratio of'K O/Na o of about 3.26/1.

, The net brine is made up aS fOllOWS 2 I Pounds KCl 29 K 00 1141 Na Co 265 H2O Of the total-K 0 produced, about 60% is as the chloride and 40 7b as the carbonate, and for each ton of K 0 there are produced 5885 pounds Na CO H O.

It will be observed that the ratio KClK CO -Na CO is substantially the same in the postassium carbonate brine produced by the fiow sheet of Figure 2 as by that of Figure 1.

' It will be understood that our process is applicable to any postassium silicate mineral whose potassium is amenable to base exchange with sodium, and to any leaching brine carrying principally the carbonates and chlorides of sodium, and whenever the terms wyomingite and Green River soda brine are employed in the appended claims, it will be understood that like or analogous materials are included.

Having thus described our invention, what u we claim and desire to secure by Letters Patent is:

1: A process for producing a carbonate brine containing a predominating amount of potassium carbonate from wyomingite' and a brine composed principally of a solution of sodium carbonate in water, which consists in grinding wyomingite and leaching under steam pressure with the said brine, removing the leach solution from the solids, evaporating so as to crystallizeout sodium carbonate mono hydrate and removing crystals of the latter salt until the mol ratio K O/Na O in the mother liquor is greater than 2.

2. A process for treating the system Na K CO Cl H O for separation of Na cO H o, KCl and K 00 which consists in evaporating to salt out Na CO H O, .cool- 1 ing the mother liquor to salt out KCl crystals, evaporating the remaining mother liquor in a secondary evaporator to salt out additional Na CO H O, cooling the mother liquor to salt out additional KCl, and circulating a portion of the last named mother liquor back through the secondary evaporator, thus leaving a brine carrying principally K 00 '3. In a process for producing salts of potassium and sodium by leaching potassium of silicate base exchange minerals with a brine carrying principally the carbonate and chlorides of sodium, the steps of separating the sodium carbonate, potassium carbonate and potassium chloride respectively, which consist in evaporating the leach liquor so as crystallize out sodium carbonate 'monohydrate, and then cooling the mother liquor to crystallize out susbtantially pure potassium chloride, evaporating the remaining mother liquor in asecondary evaporator to salt ontadditional Na CO H O, and cooling the mother liquor to salt out additional KCl, leaving a brine carrying principally potassium carbonate.

4. In a process for producing salts of potassium and sodium by leaching potassium s licate base exchange minerals with a brine carrides of sodium, the steps for separating the sodium carbonate, potassium carbonate and potassium chloride respectively, which consist in evaporating the-leach liquor so as to crystallize out sodium carbonate mono hydrate, and then cooling the mother liquor to crystallize out substantially pure potassium chloride, evaporating the remaining mother liquor in a secondary evaporator to salt out additional Na CO H O, cooling the mother liquor to salt outadditional KCl, and circulating a portion of the last named mother liquor back through the secondary evaporator, leaving a brine carrying principally potassium carbonate.

5. A process for producing potassium carbonate and potassium chloride from wyomingite and Green River soda brine which consists in grinding the wyomingite and leaching under steam pressure with a solution of sodium carbonate in Green River soda brine, removing the leach solution from the solids, evaporating so as to crystallize out sodium carbonate mono hydrate until the mother liquor is substantially saturated with respect to both sodium carbonate and potassium chloride, removing said sodium carbonate mono hydrate, cooling the mother" liquor so as to crystallize substantially pure potassium chloride, and removing the latter so as to leave a brine carrying principally potassium carbonate.

6. A process for producing potassium carbonate and potassium chloride from Wyomingite and Green Riversoda brine which con sists in grinding the wyomingite and leaching under steam pressure with a solution of sodium carbonate in Green River soda brine, removing the leach solution from the solids, evaporating so as to crystallize out sodium carbonate mono hydrate until the mother liquor is substantially saturated with respect to both sodium carbonate and potassium chloride, removing said sodium carbonate mono hydrate. cooling the mother liquor so as to crystallize substantially pure potassium chloride, removing the latter so as to leave a brine carrying principally potassium carbonate, and returning a portion of said brine in circulation to the evaporator feed.

7 In a process for producing potash salts by leaching potassium silicate base exchange minerals with a brine carrying principally the carbonates and chlorides of sodium, the steps for separating the sodium carbonate, potassium carbonate and potassium chloride respectively. which consist in evaporating the leach liquor so as to crystallize out sodium carbonate mono hydrate until the mother liquor is substantially saturated with respect to both sodium carbonate and potassium chloride, and then cooling the mother liquor to crystallize out substantially pure potassium chloride, leaving a brine carrying principally potassium carbonate.

8. A process for treating the system N a CO H O, KCl and K CO which consists in evaporating to salt out Na CO H O, cooling the mother liquor to salt out KCl crystals, and circulating a portion of the last named mother liquor back through the evaporators, thus leaving a brine carrying principally K CO 10. In a process for producing salts of potassium and sodium by leaching potassium silicate base exchange minerals with a brine carrying principally the carbonates and chlorides of sodium, the steps for separating the sodium carbonate, potassium carbonate and potassium chloride respectively, which consist in evaporating the leach liquor so as to crystallize out sodium carbonate mono hydrate, and then cooling the mother liquor to crystallize out substantially pure potassium chloride. and circulating a portion of the last named mother liquor back through the evaporator, leaving a brine carrying principally notassium carbonate. 7

11. The process of producing a liquid consisting essentially of an aqueous solution of potassium carbonate, which comprises leaching wyomingite with a hot solution of sodium potassium chloride, whereby the remaining liquid, is essentially a solution of potassium carbonate.

12. The process of producing a liquid consisting essentially of an aqueous solution of potassium carbonate, which comprises leach ing potassium silicate base exchange material with a hot solution of sodium carbonate in Green River soda brine, removing the solids present, evaporating to crystallize out sodium carbonate monohydrate until the mother liouor is substantially saturated with respect to both sodium carbonate and potassium chloride. removing said sodium carbonate monohydrate, cooling the mother liquor to crystallize out substantially pure potassium chloride, and removing said potassium chloride, whereby the remaining liquid is essentially a solution of potassium carbonate.

13. The process of producing a liquid consisting essentially of an aqueous solution of potassium carbonate, which comprises leaching wyomingitewith a hot solution of sodium carbonate in Green River soda brine, removing the solids present, evaporating to crystallize out sodium carbonate monohydrate until the mother liquor is substantially saturated with respect to both sodium carbonate and potassium chloride, removing said sodium carbonate monohydrate, cooling the mother liquor to crystallize out substantially pure potassium chloride, removing said potassium chloridelwhereby the remaining liquid is essentially a solution of potassium carbonate, and mixing a portion of said last-mentioned solution with a fresh batch to be evaporated.

14. The process of producing a liquid consisting essentially of an aqueous solution of potassium carbonate, which comprises leaching potassium silicate base exchange material with a hot solution of sodium carbonate in Green River soda brine, removing the solids present, evaporating to crystallize out sodium carbonate monohydrate until the mother liquor is substantially saturated with respect to both sodium carbonate and potassium chloride, removing said sodium carbonate monohydrate, cooling the mother liquor to crystallize out substantially pure potassium chloride, removing said potassium chloride, whereby the remaining liquid is essentially a solution of potassium carbonate, and mixing a portion of said last-mentioned solution with a fresh batch to be evaporated.

15. The process of producing a liquid contassium chloride, whereby the remaining liq-- uid is essentially a solution of potassium carbonate, dissolving said sodium carbonate monohydrate in Green River brine to form fresh leaching solution, and leaching fresh wyomingite therewith.

16.7 The process of producing a liquid consisting essentially of an aqueous solution of potassium carbonate, which comprises leaching potassium silicate base exchange material with a hot solution of sodium carbonate in Green River soda brine, removing the solids present, evaporating to crystallize out sodium carbonate monohydrate until the mother liquor is substantially saturated with respect to both sodium carbonate and potassium chloride, removing said sodium carbonate monohydrate, cooling the mother liquor ing wyomingite with a hot solution of sodium carbonate in Green River soda brine, removing the solids present, evaporating to crystallize out sodium carbonate monohydrate until the mother liquor is substantially saturated with respect to both sodium carbonate and potassium chloride, removing said sodium carbonate monohydrate, cooling the mother liquor to crystallize out substantially pure potassium chloride, removing said potassium chloride, whereby the remaining liquid is essentially a solution of potassium carbonate, mixing a portion of said last-mentioned solution with a fresh batch to be evaporated, dissolving said sodium carbonate monohydrate in Green River brine to'form fresh leaching solution,

and leaching fresh wyomingite therewith.

18. The process of producing a liquid con sisting essentially of an aqueous solution of potassium carbonate, which comprises leaching potassium silicate base exchange material with a hot solution of sodium carbonate in Green River soda brine, removing the solids present, evaporating to crystallize out sodium carbonate monohydrate until the mother liquor is substantially saturated with respect to both sodium carbonate and potassium chloride, removing said sodium carbonate monohydrate, cooling the mother liquor to crystallize out substantially pure potassium chloride, removing said potassium chloride whereby the remaining liquid is essentially a solution of potassium-carbonate, mixing a portion of said last-mentioned solution with a fresh batch to be evaporated, dissolving said sodium carbonate monohydrate in Green River brine to form fresh leaching solution, and leaching fresh potassium silicate base exchange material therewith.

. ROBERT D. PIKE.

ROSS CUMMINGSL. LEO V. STECK. 

